Figure 3:

Large gamut and switching of colors with a BA₂PbI₄ nanograting metasurface.

(A and B) Small changes in the geometrical parameters of the nanogratings, such as gap size (g = 50–200 nm), beam width (w = 50–350 nm) and milling depth (t _m = 0–240 nm) allow to access a large color gamut under, respectively, x-polarized and y-polarized incident light, thus significantly expanding on the color of the unpatterned BA₂PbI₄ perovskite film. (C and D) Numerically calculated reflection spectra of two BA₂PbI₄ perovskite metasurfaces under, respectively, x-polarized and y-polarized incident light, which show a large dynamically controllable color contrast variations of the temperature between 293 and 240 K.